Fingerprint sensing module and method for manufacturing the fingerprint sensing module

ABSTRACT

There is provided a fingerprint sensing module comprising a fingerprint sensor device having a sensing array arranged on a first side of the device. The fingerprint sensor device also comprises connection pads for connecting the fingerprint sensor device to external circuitry and a fingerprint sensor device cover structure, the cover structure having a first side configured to be touched by a finger, and a second side facing the sensing array, wherein the cover structure comprises conductive traces, arranged on the second side, for electrically connecting the fingerprint sensor module to external circuitry, and wherein a surface area of the cover structure is larger than a surface area of the sensor device. Moreover, the fingerprint sensor device comprises wire-bonds electrically connecting the connection pads of the fingerprint sensing device to the conductive traces of the cover structure.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims priority to Sweden Application No. 1651654-4,filed on Dec. 15, 2016, the disclosure of which is incorporated hereinby reference in its entirety.

FIELD OF THE INVENTION

The present invention relates to a fingerprint sensing module suitablefor integration in smart cards, and to a method for manufacturing such afingerprint sensing module. The present invention also relates to asmart card comprising such a fingerprint sensing module.

BACKGROUND OF THE INVENTION

Various types of biometric systems are used more and more in order toprovide increased security and/or enhanced user convenience. Inparticular, fingerprint sensing systems have been adopted in, forexample, consumer electronic devices, thanks to their small form factor,high performance, and user acceptance.

Among the various available fingerprint sensing principles (such ascapacitive, optical, thermal etc.), capacitive sensing is most commonlyused, in particular in applications where size and power consumption areimportant issues. All capacitive fingerprint sensors provide a measureindicative of the capacitance between each of several sensing structuresand a finger placed on or moved across the surface of the fingerprintsensor.

Moreover, fingerprint sensor integration in smart cards is increasinglyrequested by the market. However, the requirements of the fingerprintsensor in a smart card may change compared to when the sensor is used ina smartphone. For example, since the cost of a smartcard issignificantly lower than the cost of smartphone, it is even moredesirable to reduce the cost of the fingerprint sensor for a smart card.

In presently available smart cards, fingerprint sensor modules can besoldered on an inlay and the card is in turn laminated with the inlay asa center layer and with a cavity in the card upper layer leaving thefingerprint sensor module exposed upon card lamination.

However, a gap between the fingerprint sensor module and the card bodyis often visible, creating reliability and cosmetic problems. Moreover,the described process is typically only used for limited series and notsuitable for mass production.

Accordingly there is a need for an improved method for providing asmartcard comprising a fingerprint sensor module, and for a fingerprintsensor module for integration in a smart card.

SUMMARY

In view of above-mentioned and other drawbacks of the prior art, it isan object of the present invention to provide an improved fingerprintsensor module suitable for integration with a smart card, and a methodfor manufacturing such a module.

According to a first aspect of the invention, there is provided afingerprint sensing module comprising a fingerprint sensor device havinga sensing array arranged on a first side of the device, the sensingarray comprising an array of fingerprint sensing elements. Thefingerprint sensor device also comprises connection pads for connectingthe fingerprint sensor device to external circuitry. The fingerprintsensing module further comprises a fingerprint sensor device coverstructure arranged to cover the fingerprint sensor device, the coverstructure having a first side configured to be touched by a finger,thereby forming a sensing surface of the sensing module, and a secondside facing the sensing array, wherein the cover structure comprisesconductive traces, arranged on the second side of the cover structure,for electrically connecting the fingerprint sensor module to externalcircuitry, and wherein a surface area of the cover structure is largerthan a surface area of the sensor device. Moreover, the fingerprintsensor device comprises wire-bonds electrically connecting theconnection pads of the fingerprint sensing device to the conductivetraces of the cover structure.

In the present context, the fingerprint sensor device may also bereferred to as a die, a chip, a capsule or the like, and the fingerprintsensor may be a capacitive, optical or ultrasonic fingerprint sensor.

In the described fingerprint module, the sensing array faces the coverstructure such that the surface of the cover structure forms the sensingsurface of the cover structure. The described cover structure comprisesat least an insulating layer and a layer comprising the conductivetraces. However, the cover structure may equally well comprise aplurality of sub-layers.

The present invention is based on the realization that when attaching afingerprint sensing device to a cover layer comprising conductivetraces, it is advantageous to form the connection between the sensor andthe cover layer using wire bonding. Hereby, a fingerprint sensing moduleis provided which is easily integrated in a smart card by means of theconductive traces of the cover structures, as will be described infurther detail in the following. However, the described module may alsobe suitable for integrating in a wide range of applications, since amodule can be provided where e.g. the size and shape off the module canbe easily controlled by means of the cover structure.

According to one embodiment of the invention, the connection pads may bearranged on a second side of the fingerprint sensor device, opposite ofsaid first side, the fingerprint sensor device further comprising asubstrate comprising via connections reaching from the first side of thefingerprint senor device to the connection pads of the second side ofthe fingerprint sensor device. Hereby, a fingerprint sensor device isprovided where the wire bonding between the sensor device and the coverstructure is performed from the backside of the sensor device, oppositeof the sensing array. In particular, there is no need for bond wires onthe side of the fingerprint sensor comprising the sensing array.Accordingly, the described arrangement is advantageous in that thedistance between the sensing array and the outer surface of the coverstructure can be reduced, thus reducing the distance from the sensingarray and a finger placed on the sensing surface, which improved theperformance of the sensing device.

The fingerprint sensor device may also comprise wafer level fan-outtechnology for providing the connection pads used as bond pads.

According to one embodiment of the invention, the connection pads arearranged on the first side of the fingerprint sensor device, thefingerprint sensor device further comprising a carrier having a firstside attached to the second side of the fingerprint sensor device, wirebonds arranged between the connection pads of the fingerprint sensordevice and the first side of the carrier; and wire-bonds arrangedbetween a second side of the carrier, opposite of the first side, andthe conductive traces of the cover structure.

Accordingly, there is an intermediate connection between the connectionpads of the fingerprint sensor device and the connection pads of thecarrier. The connection pads of the carrier serve as bond pads forconnecting to the conductive traces of the cover structure. For someapplications, it is acceptable with a sensor device comprising bondwires on the same side as the sensing array, even though the bond wiresmay increase the minimum distance between the sensing array and a fingerplaced ion the sensing surface. The distance between the sensing arrayand the cover structure will then be determined by the bond-wire loopheight and the thickness of an overmold layer covering the sensing arrayand the bond wires. Such an arrangement may for example be used, forexample for a relatively thin cover structure. Thereby, conventionalfingerprint modules can be easily adapted in order to be used in smartcard applications.

Moreover, the fingerprint sensor device may be provided as an LGA (LandGrid Array) a lead frame based QFN-package, or by means of otherpackaging types known by the skilled person.

According to one embodiment of the invention the fingerprint sensor mayfurther comprise a mold layer arranged between the sensing device andthe cover structure. The described mold layer would serve to protect thesensing array and to provide a planar surface for attaching the sensingdevice to the cover structure.

According to one embodiment of the invention, the cover structure may bea laminate structure comprising at least one layer compromisingconductive traces and at least one insulating layer. The cover structuremay comprise one or more coating layers, comprising ink layers, toprovide a desirable visual appearance. An ink layer should herein beunderstood as any layer comprising a pigment for achieving a desiredvisual appearance. The cover structure may also comprise a layer forenhancing image capture, for example if the finger contains moisture.

According to one embodiment of the invention the fingerprint sensingmodule may further comprise one or more passive components, arranged onthe second side of the cover structure and electrically connected to theconductive traces of the cover structure.

Moreover, the passive component may also be arranged on the first sideof the carrier and electrically connected to conductive traces of thecover structure. Thereby, a fingerprint sensing module can be providedas a single module including any required passive components.

According to one embodiment of the invention the fingerprint sensingmodule may further comprise a fingerprint sensor control device attachedto a second side of the fingerprint sensing module, the second sidebeing opposite of the first side. A fingerprint sensor control devicemay for example be required for providing a drive signal of the sensingdevice, or the control device may comprise other functionality. Thecontrol device may be provided as a die, chip, capsule or the like, andis sometimes referred to as a companion chip. By providing thefingerprint sensor control device in a stacked configuration, which mayalso be referred to as a possum configuration, a complete fingerprintsensing module comprising all the required functionality can beprovided. The fingerprint sensing module is thereby ready to beincorporated in a range of applications, such as a smart card. Moreover,the stacked configuration reduces the footprint area of the fingerprintsensor module in comparison to known configurations where the sensordevice is connected to a control device located at a distance from thesensor device e.g. using a flexible film.

According to one embodiment of the invention, the fingerprint sensingmodule may further comprise wire-bonds electrically connecting thefingerprint sensor control device to conductive traces of the coverstructure. Thereby, both the fingerprint sensor device and the controldevice can be connected to the same cover structure using the sameconnection technology. Moreover, a fingerprint sensor module is providedwhere all of the required connections for operating the module arelocated on the second side of the cover structure for easy access.

According to one embodiment of the invention the fingerprint sensingmodule may further comprise a silicon interposer layer arranged betweenthe fingerprint sensor control device and the second side of saidfingerprint sensing module. The interposer layer can be electricallyconnected by wire bonding to the cover structure and it may for examplebe used to form electrical connections between the control device andthe sensor device. For example, the interposer layer may be used forrouting signals between the two devices. The interposer layer may alsocomprise passive components required fro the operating of the sensingmodule.

Additionally, the fingerprint sensing module may comprise a mechanicalsupport layer arranged between the fingerprint sensor control device andthe second side of said fingerprint sensing module. The mechanicalsupport layer can for example be a compliant polymer based material. Amechanical support layer may increase the flexibility of the sensingmodule, allowing the module to flex more without breaking. This may beparticularly advantageous for a sensing module integrated in a smartcard, due to the flexibility of the smart card.

According to one embodiment of the invention, the fingerprint sensingmodule may further comprise an electrically conductive bezel arrangedadjacent to the sensing array to provide an electrical connectionbetween a finger placed on the sensing surface and drive signalcircuitry of the fingerprint sensing module. The bezel may for examplebe a frame arranged to surround the sensor device such that a fingerplaced on the sensing surface also makes contact with the bezel.Thereby, a drive signal can be provided to the finger, which facilitatescapacitive fingerprint measurement according to established sensingtechnology. In case of the cover structure being a laminate structurecomprising a plurality of conductive layers, the top metal layer in thelaminate structure may advantageously be used to form an electricalcontact to the bezel. It should however be noted that the sensing moduleequally well may operate without a bezel, in which case a drive signalmay be provided to a sensing element of the sensing array, or to areference ground level of the fingerprint sensing device.

According to one embodiment of the invention, the cover structureextends outside of the fingerprint sensor device such that thefingerprint sensing module has a T-shaped profile. In other words, thecover structure extends outside of the surface of the sensor device onat least two opposing sides of the sensing device. In case of a squareor rectangular sensing module, the cover structure may extend outside ofthe sensor device on all four sides of the sensor device. Accordingly itis possible to provide connections on the underside of the coverstructure on at least two sides sensor device, thereby increasing thevarious possible ways to connect the fingerprint sensor module to a anelectronic device, a smart card and the like. Moreover, a fingerprintsensing module having a T-shaped profile can easily be placed in acorresponding recess or opening, as will be described in further detailin the following.

According to one embodiment of the invention the cover structure may beflexible, such as a flex film or the like, thereby facilitatingintegration of the fingerprint sensing module in smart cards wherein itis particularly desirable to have flexible module due to the flexibilityof the card itself. Through a flexible cover layer, the fingerprintmodule can flex and follow a bending of e.g. a smart card without thesensing device itself having to be flexible.

However, it should be noted that the cover structure equally well berigid, such as a glass or ceramic structure, which may be more suitablefor integrating the fingerprint sensing module in other types ofdevices. The cover structure may for example be a protective plate, acover glass or a display glass comprising conductive traces.

According to one embodiment of the invention, the fingerprint sensingmodule may advantageously comprise a secure element, which is oftenrequired in a smart card to provide a secure memory and executionenvironment. The secure element may for example be included in a stackcomprising the fingerprint sensor device and, optionally, thefingerprint sensor control device. However, the secure element can alsobe arranged in other locations, such as on a carrier or on the coverstructure.

According to one embodiment of the invention, there is provided a smartcard comprising a fingerprint sensing module according to any one of theabove described embodiment. The smart card comprises a recess into whichthe fingerprint sensing module is arranged, wherein the cover structureof the fingerprint sensing module comprises connection pads forconnecting the conductive traces to corresponding connection pads of aconductive inlay of said smart card. Thereby, a smart card is formedwherein the fingerprint sensor device and any associated circuitry canbe easily connected to smart card circuitry by means of the connectionpads of the cover layer. In particular, the sensing module can beconnected to circuitry of the smart card handling authentication and/orverification of an identity of a user so as to provide increasedsecurity in connection with use of the smart card. The smart card mayfor example be used for authorizing a financial transaction, forverifying an identity and/or for granting access. A smart card can beconsidered to be any pocket-sized card that has embedded integratedcircuits.

According to one embodiment of the invention the recess of the smartcard may advantageously have a shape corresponding to a shape of thefingerprint sensing module. Thereby, the fingerprint sensing module canbe fitted into the recess with a minimal or no gap between the outerlayer of the smart card and the sensing module. The recess may forexample be T-shaped and configured to receive a correspondingly T-shapedfingerprint sensing module.

According to a second aspect of the invention, there is provided amethod for manufacturing a fingerprint sensing module comprisingproviding a fingerprint sensor device having a sensing array arranged ona first side of the device, the sensing array comprising an array offingerprint sensing elements, wherein the fingerprint sensor devicecomprises connection pads for connecting the fingerprint sensor deviceto external circuitry, providing a fingerprint sensor device coverstructure comprising conductive traces, arranged on the second side ofthe cover structure, for electrically connecting the fingerprint sensormodule to the external circuitry; attaching the fingerprint sensordevice to the cover structure; and electrically connecting thefingerprint sensor device by means of wire bonding between theconnections pads and said conductive traces.

Hereby, a method for manufacturing a fingerprint sensing module isprovided which can be performed using convention processing steps wellknown in the field of microelectronic manufacturing. Accordingly, thedescribed module can be manufactured using existing processes.

It should be noted that the cover structure may also comprise connectionpads for facilitating wire bonding.

According to one embodiment of the invention, the method may furthercomprise attaching a fingerprint sensor control device to a second sideof the fingerprint sensing module, the second side being opposite of thefirst side. Thereby, the fingerprint control circuit can be formed in astacked arrangement with the sensing device, providing a convenientmodule where the control circuit functionality is integrated in the samemodule as the sensing device.

According to one embodiment of the invention, the method may furthercomprise encapsulating the fingerprint sensing module. Encapsulatingmeans that the backside of the module, i.e. the side opposite the sideof the cover structure acting as sensing surface, is encapsulated usinga cap or mold material in order to protect the devices of the module andto provide a module which is easy to handle. At least a portion of theconductive traces of the cover structure, and in particular theconnection pads used to connect to the sensor device via the conductivetraces, is not covered by the encapsulation in order to enableconnection of the fingerprint sensing module to external circuitry.Wire-bond and encapsulation processes on 35-mm wide reel-to reel formatare today common in secure element module production for smart cards.

Additional effects and features of the second aspect of the inventionare largely analogous to those described above in connection with thefirst aspect of the invention.

According to a third aspect of the invention, there is provided a methodfor manufacturing a smart card comprising a fingerprint sensing moduleaccording to any one of the above described embodiments, the methodcomprising: providing a smart card substrate comprising a plurality oflayers; forming a recess in the smart card, the recess comprising alower portion and an upper portion, the upper portion having an arealarger than an area of the lower portion; forming via connectionsbetween the upper portion of the recess and conductive traces of thesmart card; and arranging a sensing module in the recess such that theconductive traces of the cover layer form an electrical contact with thevia connections.

The smart card substrate may be a conventional laminate smart cardsubstrate comprising one or more electrically conductive layerssandwiched between a plurality of insulating layers. The upper and lowerportions of the recess together form a recess advantageously have aprofile corresponding to a T-shape, for receiving a T-shaped fingerprintmodule. Moreover, the module may be attached to the smart card using aflexible conductive adhesive to at the same time form an electricalconnection between the conductive traces of the cover structure and aconductive inlay of the smart card, in order to electrically connect thefingerprint sensing module to smart card circuitry.

Most payment cards today are laminated with a conductive inlay at thecenter of the card. A process referred to as milling and drilling istypically used to create the cavity for secure element integration inthe smart card. According to various embodiments of the describedinvention, such a “mill and drill” technique can be used to for a recessfor receiving the fingerprint sensing module. Thereby, existingmanufacturing methods for smart cards can be used to also integrate afingerprint sensor, thereby lowering the threshold for fingerprintsensor integration in smart cards.

Additional effects and features of the third aspect of the invention arelargely analogous to those described above in connection with the firstand second aspects of the invention.

Further features of, and advantages with, the present invention willbecome apparent when studying the appended claims and the followingdescription. The skilled person realize that different features of thepresent invention may be combined to create embodiments other than thosedescribed in the following, without departing from the scope of thepresent invention.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other aspects of the present invention will now be describedin more detail, with reference to the appended drawings showing anexample embodiment of the invention, wherein:

FIG. 1 schematically illustrates a smart card according to an embodimentof the invention;

FIG. 2 schematically illustrates a fingerprint sensing module accordingto an embodiment of the invention;

FIG. 3 schematically illustrates a fingerprint sensing module accordingto an embodiment of the invention;

FIG. 4 schematically illustrates a fingerprint sensing module accordingto an embodiment of the invention;

FIG. 5 schematically illustrates a fingerprint sensing module accordingto an embodiment of the invention;

FIG. 6 is a flow chart outlining the general steps of a method ofmanufacturing a fingerprint sensing module according to an embodiment ofthe invention; and

FIGS. 7A-G schematically illustrate a method of manufacturing a smartcard according to an embodiment of the invention.

DETAILED DESCRIPTION OF EXAMPLE EMBODIMENTS

In the present detailed description, various embodiments of the moduleand method according to the present invention are mainly described withreference to a fingerprint sensing module comprising a capacitivefingerprint sensor. Moreover, the fingerprint sensing module isdescribed with reference to integration in a smart card. However, thedescribed module may also be well suited for use in other applications,such a consumer electronic devices, internet-of-things (IoT) andautomotive applications.

FIG. 1 schematically illustrates a smart card 1 comprising fingerprintsensing module 2 according to an embodiment of the invention.

FIG. 2 schematically illustrates a fingerprint sensing module 2comprising a fingerprint sensor device 20 having a sensing array 21arranged on a first side 22 of the device 20. The sensing array 21comprises an array of fingerprint sensing elements, here electricallyconducting plates, configured to detect a capacitive coupling betweeneach sensing element and a finger placed on a sensing surface of thesensing module 2. The fingerprint sensor device 20 further comprisesconnection pads 24 for connecting the fingerprint sensor device 20 toexternal circuitry (not shown). The external circuitry may for examplebe an integrated circuit in a smart card.

The fingerprint sensing module 2 further comprises a fingerprint sensordevice cover structure 30 arranged to cover the fingerprint sensordevice 21. The cover structure has a first side 32 configured to betouched by a finger, thereby forming a sensing surface 32 of the sensingmodule 2, and a second side 34 facing the sensing array 21. Moreover,the cover structure comprises conductive traces 35, arranged on thesecond side 34 of the cover structure 30, for electrically connectingthe fingerprint sensor module 2 to the external circuitry. As can beseen in FIG. 2, a surface area of the cover structure 30 is larger thana surface area of the sensor device 20, such that the conductive traces35 of the sensing module 2 can be connected to corresponding connectionpads at a surface facing the same direction as the sensing surface 32.Finally, the fingerprint sensing module 2 further comprises wire-bonds40 electrically connecting the connection pads 24 of the fingerprintsensing device 20 to the conductive traces 35 of the cover structure 30.Here, the connection pads 24 are arranged on the second side 23 of thesensor device 20 electrically connected to the sensing array 21 andassociated sensing and readout circuitry by means of via connections 52through the sensor substrate 50.

In the illustrated embodiment, a conventional fingerprint sensing devicecan be used, wherein an existing backside connection can be used to wirebond to the conductive traces 35 of the cover structure. Moreover, inthe sensing module 2 illustrated in FIG. 2, the sensing array 21 is veryclose to the exterior surface 32 of the sensing module, i.e. the sensingsurface, which in turn leads to a good capacitive coupling between afinger placed on the sensing surface and the sensing elements of thesensing array 21. In a smart card, the cover structure 30 can be madethin, whereas for under-glass applications, for example when afingerprint sensor is arranged under a display glass, the glassthickness is preferably at least 300 μm. In comparison, according tocurrent ISO-standards, the total thickness of the smart card should be760 μm.

FIG. 3 schematically illustrates a fingerprint sensing module 2according to an embodiment of the invention. In addition to thecomponents described above with reference to FIG. 2, the fingerprintsensing module 2 of FIG. 3 further comprises a passive component 70,arranged on the second side 34 of the cover structure 30 andelectrically connected to conductive traces 35 of the cover structure30. One or more passive components 70 may be arranged directly on thecover structure 30 as individual components, as capsules or asintegrated passive devices (IPD:s).

Moreover, FIG. 3 also illustrates a fingerprint sensor control device 80attached to a second side 23 of the fingerprint sensing device 20, thesecond side 23 being opposite of the first side 22. The fingerprintsensor control device 80 is connected to conductive traces 35 of thecover structure 30 by means of bond wires 82. An additional option, notillustrated herein, is to arrange passive components on the backside ofthe control device, and to connect also the passive components toexternal circuitry by wire bonding down to the conductive traces 35 ofthe cover structure 30.

FIG. 4 schematically illustrates a fingerprint sensing module 2according to an embodiment of the invention where the connection pads 24of the fingerprint sensor device 20 are arranged on the first side 22 ofthe fingerprint sensor device 20. In the illustrated embodiment, thefingerprint sensor device 20 is arranged on a carrier 60 having a firstside 61 attached to the second side 23 of the fingerprint sensor device20. The carrier 60 may for example be a flexible substrate or a PCB. Thefingerprint sensor device 20 is connected via wire bonds 64 from theconnection pads 24 of the fingerprint sensor device 20 to the first sideof the carrier 60. The electrical connection 65 is then formed throughthe carrier 60 and further on to conductive traces 35 of the coverstructure 30 by means of wire-bonds 66 connected between the second sideof the carrier 60, opposite of the first side 61, and the conductivetraces 35.

The fingerprint sensing module of FIG. 5 is largely similar to themodule illustrated in FIG. 4. A difference is that an additional layer84 is located between the carrier 60 and the fingerprint control device80. In one embodiment, the layer 84 is a silicon interposer layer 84which may be used to route signals between the two devices, 20, 80 andit may also comprise integrated passive components. The interposer layer84 is illustrated to comprise wire-bonds 85 connecting the interposer tothe cover structure 30. In another embodiment, the layer 84 may be amechanical support layer protecting the devices of the module, in whichcase there is no need for wire-bonding. The circuitry of the fingerprintsensor device 20 and the fingerprint sensor control device 80 istypically made in silicon, which in general is a rigid material, eventhough silicon can be flexible in sufficiently thin layers. However, bymeans of the mechanical support layer, the silicon devices may achieveadditional flexibility without breaking.

FIG. 6 is a flow chart outlining the general steps of a method formanufacturing a fingerprint sensing module according to an embodiment ofthe invention. The method will be described with reference to FIG. 2,illustrating an embodiment of the fingerprint sensing module 2. Themethod comprises providing 102 a fingerprint sensor device 20 andproviding 104 a fingerprint sensor device cover structure 30 comprisingconductive traces for electrically connecting the fingerprint sensormodule 2 to external circuitry. Next, the fingerprint sensor device 20is attached to the cover structure 30 and electrically connected saidfingerprint sensor device 20 by means of wire bonding 108 between theconnection pad 24 of the fingerprint sensor device 20 and the conductivetraces 35 of the cover structure 30. In a final step, the side of themodule 2 comprising the wire bonds 82, 85 is encapsulated 110 in orderto protect the bond wires and the devices.

FIGS. 7A-G schematically illustrate a method of manufacturing a smartcard comprising a fingerprint sensing module according to any of theembodiments described herein.

FIG. 7A illustrates a laminate smart card substrate 90 comprising aplurality of layers. Forming the smart card comprises milling anddrilling the top layer of the smart card substrate 90 to form a recess91. The recess 90 comprises an upper portion 92 and a lower portion 93,where the upper portion 92 has an area larger than an area of the lowerportion 93, thereby a T-shaped recess is formed.

FIG. 7c illustrates openings 94 drilled from the upper portion of therecess 92 down to a conductive layer 95 of the smart card substrate. Thesmart card may in practice comprise a plurality of layers. However, forsimplicity, only one conductive layer is illustrated. The conductivelayer(s) of the smart card comprise conductive traces for connecting thefingerprint sensing module 2 to an integrated circuit of the smart card.

In FIG. 7D, a conductive material is arranged in the openings 94 to formconductive via connections 96 to the conductive layer 95.

FIG. 7E illustrates providing a sensing module 2 having T-shapecorresponding to the T-shape of the recess 91, and in FIG. 7F, thesensing module is arranged in the recess. In particular, the conductivetraces 35 of the cover structure 30 are located such that they form anelectrical connection with the via connections 96 of the smart card. Thefingerprint sensing module 2 is advantageously attached to the smartcard substrate 90 using a conductive adhesive 97 at the locations of thevia connections 96.

In a final step, illustrated in FIG. 7D, the adhesive 97 is heated usinga heating tool 98 to cure the adhesive. Instead of using a conductiveadhesive, it is also possible to use a low temperature solder material,where the soldering temperature is sufficiently low to prevent meltingthe smart card substrate.

The various embodiments of a fingerprint sensing module illustratedherein comprises one control device, one passive component etc. However,the skilled person readily realizes that the described module mayequally well comprise two or more of the various described devices andcomponents.

Moreover, even though the invention has been described with reference tospecific exemplifying embodiments thereof, many different alterations,modifications and the like will become apparent for those skilled in theart. Also, it should be noted that parts of the module, smart card andmethod may be omitted, interchanged or arranged in various ways, themodule, smart card and method yet being able to perform thefunctionality of the present invention.

Additionally, variations to the disclosed embodiments can be understoodand effected by the skilled person in practicing the claimed invention,from a study of the drawings, the disclosure, and the appended claims.In the claims, the word “comprising” does not exclude other elements orsteps, and the indefinite article “a” or “an” does not exclude aplurality. The mere fact that certain measures are recited in mutuallydifferent dependent claims does not indicate that a combination of thesemeasures cannot be used to advantage.

1. A fingerprint sensing module comprising: a fingerprint sensor devicehaving a sensing array arranged on a first side of the device, thesensing array comprising an array of fingerprint sensing elements,wherein said fingerprint sensor device comprises connection pads forconnecting said fingerprint sensor device to external circuitry; afingerprint sensor device cover structure arranged to cover saidfingerprint sensor device, said cover structure having a first sideconfigured to be touched by a finger, thereby forming a sensing surfaceof said sensing module, and a second side facing said sensing array,wherein said cover structure comprises conductive traces arranged on thesecond side of the cover structure, for electrically connecting saidfingerprint sensing module to external circuitry, and wherein a surfacearea of said cover structure is larger than a surface area of saidsensor device; wherein said fingerprint sensor device further compriseswire-bonds electrically connecting said connection pads of saidfingerprint sensor device to said conductive traces of said coverstructure.
 2. The fingerprint sensing module according to claim 1,wherein said connection pads are arranged on a second side of saidfingerprint sensor device, opposite of said first side of saidfingerprint sensor device, said fingerprint sensor device furthercomprising a substrate comprising via connections reaching from saidfirst side of said fingerprint senor device to said connection pads ofsaid second side of said fingerprint sensor device.
 3. The fingerprintsensing module according to claim 1, wherein said connection pads arearranged on said first side of said fingerprint sensor device, saidfingerprint sensor device further comprising: a carrier having a firstside attached to said a second side of said fingerprint sensor device,opposite of said first side of said fingerprint sensor device;wire-bonds between said connection pads of said fingerprint sensordevice and said first side of said carrier; and wire-bonds arrangedbetween a second side of said carrier, opposite of said first side ofsaid carrier, and said conductive traces of said cover structure.
 4. Thefingerprint sensing module according claim 1, further comprising moldlayer arranged between said sensor device and said cover structure. 5.The fingerprint sensing module according to claim 1, wherein said coverstructure is a laminate structure comprising at least one layercomprising conductive traces and at least one insulating layer.
 6. Thefingerprint sensing module according to claim 1, further comprising apassive component, arranged on said second side of said cover structureand electrically connected to the conductive traces of said coverstructure.
 7. The fingerprint sensing module according to claim 3,further comprising a passive component arranged on said first side ofsaid carrier and electrically connected to conductive traces of saidcover structure.
 8. The fingerprint sensing module according to claim 1,further comprising: a fingerprint sensor control device attached to asecond side of said fingerprint sensor device, said second side beingopposite of said first side of said fingerprint sensor device.
 9. Thefingerprint sensing module according to claim 8, further comprisingwire-bonds electrically connecting said fingerprint sensor controldevice to conductive traces of said cover structure.
 10. The fingerprintsensing module according to claim 8, further comprising a siliconinterposer layer arranged between said fingerprint sensor control deviceand said second side of said fingerprint sensor device.
 11. Thefingerprint sensing module according to claim 1, further comprising anelectrically conductive bezel arranged adjacent to said sensing array toprovide an electrical connection between a finger placed on said sensingsurface and drive signal circuitry of said fingerprint sensing module.12. The fingerprint sensing module according to claim 1, wherein saidcover structure extends outside of said fingerprint sensor device suchthat said fingerprint sensing module has a T-shaped profile.
 13. Thefingerprint sensing module according to claim 1, wherein said coverstructure is flexible.
 14. The fingerprint sensing module according toclaim 1, further comprising a secure element.
 15. A smart cardcomprising a fingerprint sensing module according to claim 1; said smartcard comprising a recess into which said fingerprint sensing module isarranged; wherein said cover structure of said fingerprint sensingmodule comprises connection pads for connecting said conductive tracesto corresponding connection pads of a conductive inlay of said smartcard.
 16. The smart card according to claim 15, wherein said recess hasa shape corresponding to a shape of said fingerprint sensing module. 17.The smart card according to claim 15, wherein said recess is T-shapedand configured to receive a correspondingly T-shaped fingerprint sensingmodule.
 18. A method for manufacturing a fingerprint sensing modulecomprising: providing a fingerprint sensor device having a sensing arrayarranged on a first side of the device, the sensing array comprising anarray of fingerprint sensing elements, wherein said fingerprint sensordevice comprises connection pads for connecting said fingerprint sensordevice to external circuitry; providing a fingerprint sensor devicecover structure comprising conductive traces, arranged on the secondside of the cover structure, for electrically connecting saidfingerprint sensing module to the external circuitry; attaching saidfingerprint sensor device to said cover structure; electricallyconnecting said fingerprint sensor device by means of wire bondingbetween said connections pads and said conductive traces.
 19. The methodaccording to claim 18, further comprising attaching a fingerprint sensorcontrol device to a second side of said fingerprint sensor device, saidsecond side being opposite of said first side of said fingerprint sensordevice.
 20. The method according to claim 18, further comprisingencapsulating said fingerprint sensing module.
 21. A method formanufacturing a smart card comprising a fingerprint sensing moduleaccording to claim 1, the method comprising: providing a smart cardsubstrate comprising a plurality of layers; forming a recess in saidsmart card, said recess comprising a lower portion and an upper portion,said upper portion having an area larger than an area of said lowerportion; forming via connections between said upper portion of saidrecess and conductive traces of the smart card; and arranging a sensingmodule in said recess such that said conductive traces of said coverstructure form an electrical contact with said via connections.